Energy Management in Passerine Birds during the Nonbreeding Season

Pravosudov, Vladimir V.; Grubb, Thomas C.

doi:10.1007/978-1-4757-9915-6_5

Cited by 95 publications

(83 citation statements)

References 128 publications

(230 reference statements)

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“…McGowan et al 2002;Stillman and Goss-Custard 2002). This is because without sufficient fat reserves birds would inevitably starve because foraging is unpredictable and energy costs are high, and in some small species, starvation will occur overnight without fat reserves (Pravosudov et al 1997). Mortality due to predation is however less certain: predators may have a range of prey individuals to choose from, and if attacked, capture may not occur.…”

Section: High Costs Of Compensating For Predation Riskmentioning

confidence: 99%

Predation in bird populations

Cresswell

2010

J Ornithol

240

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One of the classic ecological questions is how predators affect population size. This is often assessed by measuring how many individuals are killed by a predator, yet such direct effects may only be a relatively minor part of population dynamics. Predators frequently affect prey populations indirectly, with the fear of predation resulting in costly behavioural compensation leading to potentially large population and community effects. Large observable lethal effects may then just represent the most easily observed "special" cases of the effects of predation on populations, with the costs of non-lethal effects being ubiquitous and usually dominant. This review explores these two ideas: that cases where there are no population effects due to predation, and cases where lethal effects dominate, are unusual and involve special circumstances. First, systems where predation effects appear not to arise include complete avoidance of predators by prey; when other environmental factors limit populations so that predation is not additive to mortality; when there are other more vulnerable prey for a predator; when predators interact; because the relationship of perceived predation risk with predator abundance is usually a non-linear function, and simply because non-lethal effects have not been considered. Second, lethal effects tend to dominate over non-lethal effects when there is a high cost of compensating for predation risk associated with either resource constraint or a particularly vulnerable niche or life history stage (e.g. the nest stage generally for birds); when prey are the most popular prey of a predator or linear trophic chains operate; when there is evolutionary lag such as introduced predators and naïve prey populations; and when there are several predator species hunting the same prey in diverse ways. The presence of predators may or may not affect the size of a bird population at any particular life history stage, although in most cases it will through non-lethal effects and occasionally through lethal effects.But the presence of predators will always affect intra-and interspecific competition and so will always affect population dynamics. Studies that wish to fully demonstrate that predation has no effect on bird populations must show that lethal effects and the costs of non-lethal compensation by the prey do not significantly change its density and so the level of competition.3

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Section: High Costs Of Compensating For Predation Riskmentioning

confidence: 99%

Predation in bird populations

Cresswell

2010

J Ornithol

240

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“…We hypothesized that the evolutionary pressure on cache retrieval e¤ciency may vary during the year because of ecological di¡erences in energy demands. Food caches represent an important energy source, one that complements body fat and signi¢-cantly decreases the probability of death from starvation (Pravosudov & Grubb 1997). If a bird is ine¤cient at ¢nding its caches during late summer when food is plentiful and it is easy for a bird to maintain its energy balance, then such a lapse should not have a strong e¡ect on its survival.…”

Section: Introductionmentioning

confidence: 99%

Effects of demanding foraging conditions on cache retrieval accuracy in food-caching mountain chickadees (Poecile gambeli)

Pravosudov

Clayton

2001

Proc. R. Soc. Lond. B

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Birds rely, at least in part, on spatial memory for recovering previously hidden caches but accurate cache recovery may be more critical for birds that forage in harsh conditions where the food supply is limited and unpredictable. Failure to ¢nd caches in these conditions may potentially result in death from starvation. In order to test this hypothesis we compared the cache recovery behaviour of 24 wild-caught mountain chickadees (Poecile gambeli), half of which were maintained on a limited and unpredictable food supply while the rest were maintained on an ad libitum food supply for 60 days. We then tested their cache retrieval accuracy by allowing birds from both groups to cache seeds in the experimental room and recover them 5 hours later. Our results showed that birds maintained on a limited and unpredictable food supply made signi¢cantly fewer visits to non-cache sites when recovering their caches compared to birds maintained on ad libitum food. We found the same di¡erence in performance in two versions of a one-trial associative learning task in which the birds had to rely on memory to ¢nd previously encountered hidden food. In a non-spatial memory version of the task, in which the baited feeder was clearly marked, there were no signi¢cant di¡erences between the two groups. We therefore concluded that the two groups di¡ered in their e¤ciency at cache retrieval. We suggest that this di¡erence is more likely to be attributable to a di¡erence in memory (encoding or recall) than to a di¡erence in their motivation to search for hidden food, although the possibility of some motivational di¡erences still exists. Overall, our results suggest that demanding foraging conditions favour more accurate cache retrieval in food-caching birds.

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“…An understanding of behavioral ecology allows one to pose questions about the selective pressures that drive the evolution of cognitive abilities in food-caching birds, and how a bird's decisions concerning both caching and cache-recovery are shaped by ecological factors. For example, reliance on cached food may be greater for those individuals that live in harsher environments, where access to food supplies is limited and unpredictable because failure to recover food caches in the winter may lead to death from starvation (Pravosudov & Grubb, 1997). The prediction, therefore, is that an individual living in harsh conditions should cache more food and/or show more efficient recovery of caches (e.g., fewer searches to find its cached seeds) than one that lives in a more temperate environment.…”

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The Comparative Cognition of Caching

Kort¹,

Tebbich²,

Dally³

et al. 2009

Comparative CognitionExperimental Explorations of Animal Intelligence

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The avian food-caching paradigm has greatly contributed to our understanding of a number of cognitive capacities. Although the early work focused on spatial memory, contemporary studies of the cognitive abilities of food-caching birds have a much broader scope, ranging from episodic-like memory and mental time travel to aspects of social cognition such as observational spatial memory of other birds' caches and elements of mental attribution. A major strength of using the food-caching paradigm to test for cognitive abilities lies in the combination of ethological validity coupled with rigorous experimental control. Thus, food-caching is a naturally occurring behavior, but one that birds will readily perform in the laboratory. And, unlike many of the standard psychological tests of animal memory, the birds do not need to be trained to cache or recover. Yet, the very fact that memory for food caches can be tested in captive birds allows a level of control that would be difficult, if not impossible, in the field. For example, we can control for the time elapsed between caching and the first opportunity to recover that cache, as well as whether or not the animal can use cues emanating directly from the caches at the time of recovery. And, we can test hand-raised birds that have spent their life in captivity, ones whose reinforcement histories are well documented and whose previous experiences can be experimentally manipulated. 2Our current approach to the comparative cognition of caching capitalizes on an integrative knowledge of behavioral ecology and comparative psychology. An understanding of behavioral ecology allows one to pose questions about the selective pressures that drive the evolution of cognitive abilities in food-caching birds, and how a bird's decisions concerning both caching and cache-recovery are shaped by ecological factors. For example, reliance on cached food may be greater for those individuals that live in harsher environments, where access to food supplies is limited and unpredictable because failure to recover food caches in the winter may lead to death from starvation (Pravosudov & Grubb, 1997). The prediction, therefore, is that an individual living in harsh conditions should cache more food and/or show more efficient recovery of caches (e.g., fewer searches to find its cached seeds) than one that lives in a more temperate environment. Support for this claim comes from population differences in the caching behavior of black-capped chickadees (Poecile atricapillus). Alaskan chickadees that have to endure severely cold winters cache considerably more seeds and are much more efficient at cache recovery than chickadees from low elevation Colorado, even when the two populations are housed for 2 months in identical conditions in the laboratory (Pravosudov & Clayton, 2002).In comparative psychology, the emphasis is on understanding general processes of learning, memory, and cognition, and the questions are often inspired by the logical structure of the task. Adopting a psychological approach allow...

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Energy Management in Passerine Birds during the Nonbreeding Season

Cited by 95 publications

References 128 publications

Predation in bird populations

Predation in bird populations

Effects of demanding foraging conditions on cache retrieval accuracy in food-caching mountain chickadees (Poecile gambeli)

The Comparative Cognition of Caching

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